Android 自定义View实践之组合控件实现布局的复用

看到很多项目会有实现自己的标题栏的做法，通常的界面是左边按钮或文字，加上中间的标题和右边的按钮或文字组成的。比较好的一种做法是使用include标签，复用同一个xml文件来实现布局的复用。但是这种方法是通过代码的方式来设置标题，左右按钮等其他的属性，会导致布局属性和Activity代码耦合性比较高。

因此，我们要通过自定义View，继承ViewGroup子类来实现这样的布局，降低布局文件和Activity代码耦合性。

1. 首先，我们需要写出布局文件layout_custom_titlebar.xml。

<?xml version="1.0" encoding="utf-8"?>
<merge xmlns:android="http://schemas.android.com/apk/res/android">
<!-- 使用merge标签减少层级 -->
<Button
    android:id="@+id/title_bar_left"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentLeft="true"
    android:layout_centerVertical="true"
    android:layout_marginLeft="5dp"
    android:background="@null"
    android:minHeight="45dp"
    android:minWidth="45dp"
    android:textSize="14sp" />

<TextView
    android:id="@+id/title_bar_title"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerInParent="true"
    android:singleLine="true"
    android:textSize="17sp" />

<Button
    android:id="@+id/title_bar_right"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentRight="true"
    android:layout_centerVertical="true"
    android:layout_marginRight="7dp"
    android:background="@null"
    android:minHeight="45dp"
    android:minWidth="45dp"
    android:textSize="14sp" />

</merge>

2.定义自定义属性

<declare-styleable name="CustomTitleBar">
    <!--标题栏背景色-->
    <attr name="title_background_color" format="reference|integer" />
    <!--左边按钮是否可见-->
    <attr name="left_button_visible" format="boolean" />
    <!--右边按钮是否可见-->
    <attr name="right_button_visible" format="boolean" />
    <!--标题文字-->
    <attr name="title_text" format="string" />
    <!--标题文字颜色-->
    <attr name="title_text_color" format="color" />
    <!--标题文字图标-->
    <attr name="title_text_drawable" format="reference|integer" />
    <!--左边按钮文字-->
    <attr name="left_button_text" format="string" />
    <!--左边按钮文字颜色-->
    <attr name="left_button_text_color" format="color" />
    <!--左边按钮图标-->
    <attr name="left_button_drawable" format="reference|integer" />
    <!--右边按钮文字-->
    <attr name="right_button_text" format="string" />
    <!--右边按钮文字颜色-->
    <attr name="right_button_text_color" format="color" />
    <!--右边按钮图标-->
    <attr name="right_button_drawable" format="reference|integer" />
</declare-styleable>

3.自定义一个View继承ViewGroup子类，这里我们继承RelativeLayout。

public class CustomTitleBar extends RelativeLayout {
private Button titleBarLeftBtn;
private Button titleBarRightBtn;
private TextView titleBarTitle;

public CustomTitleBar(Context context) {
    super(context);
}

public CustomTitleBar(Context context, AttributeSet attrs) {
    super(context, attrs);

    LayoutInflater.from(context).inflate(R.layout.layout_custom_titlebar,this,true);
    titleBarLeftBtn = (Button) findViewById(R.id.title_bar_left);
    titleBarRightBtn = (Button) findViewById(R.id.title_bar_right);
    titleBarTitle = (TextView) findViewById(R.id.title_bar_title);

    TypedArray typedArray=context.obtainStyledAttributes(attrs,R.styleable.CustomTitleBar);
    if(typedArray!=null){
        //titleBar背景色
        int titleBarBackGround=typedArray.getResourceId(R.styleable.CustomTitleBar_title_background_color, Color.BLUE);
        setBackgroundColor(titleBarBackGround);

        //获取是否要显示左边按钮
        boolean leftButtonVisible = typedArray.getBoolean(R.styleable.CustomTitleBar_left_button_visible, true);
        if (leftButtonVisible) {
            titleBarLeftBtn.setVisibility(View.VISIBLE);
        } else {
            titleBarLeftBtn.setVisibility(View.INVISIBLE);
        }
        //设置左边按钮的文字
        String leftButtonText = typedArray.getString(R.styleable.CustomTitleBar_left_button_text);
        if (!TextUtils.isEmpty(leftButtonText)) {
            titleBarLeftBtn.setText(leftButtonText);
            //设置左边按钮文字颜色
            int leftButtonTextColor = typedArray.getColor(R.styleable.CustomTitleBar_left_button_text_color, Color.WHITE);
            titleBarLeftBtn.setTextColor(leftButtonTextColor);
        } else {
            //设置左边图片icon 这里是二选一 要么只能是文字 要么只能是图片
            int leftButtonDrawable = typedArray.getResourceId(R.styleable.CustomTitleBar_left_button_drawable, R.mipmap.titlebar_back_icon);
            if (leftButtonDrawable != -1) {
                titleBarLeftBtn.setBackgroundResource(leftButtonDrawable);
            }
        }

        //先获取标题是否要显示图片icon
        int titleTextDrawable = typedArray.getResourceId(R.styleable.CustomTitleBar_title_text_drawable, -1);
        if (titleTextDrawable != -1) {
            titleBarTitle.setBackgroundResource(titleTextDrawable);
        } else {
            //如果不是图片标题 则获取文字标题
            String titleText = typedArray.getString(R.styleable.CustomTitleBar_title_text);
            if (!TextUtils.isEmpty(titleText)) {
                titleBarTitle.setText(titleText);
            }
            //获取标题显示颜色
            int titleTextColor = typedArray.getColor(R.styleable.CustomTitleBar_title_text_color, Color.WHITE);
            titleBarTitle.setTextColor(titleTextColor);
        }

        //获取是否要显示右边按钮
        boolean rightButtonVisible = typedArray.getBoolean(R.styleable.CustomTitleBar_right_button_visible, true);
        if (rightButtonVisible) {
            titleBarRightBtn.setVisibility(View.VISIBLE);
        } else {
            titleBarRightBtn.setVisibility(View.INVISIBLE);
        }
        //设置右边按钮的文字
        String rightButtonText = typedArray.getString(R.styleable.CustomTitleBar_right_button_text);
        if (!TextUtils.isEmpty(rightButtonText)) {
            titleBarRightBtn.setText(rightButtonText);
            //设置右边按钮文字颜色
            int rightButtonTextColor = typedArray.getColor(R.styleable.CustomTitleBar_right_button_text_color, Color.BLUE);
            titleBarRightBtn.setTextColor(rightButtonTextColor);
        } else {
            //设置右边图片icon 这里是二选一 要么只能是文字 要么只能是图片
            int rightButtonDrawable = typedArray.getResourceId(R.styleable.CustomTitleBar_right_button_drawable, -1);
            if (rightButtonDrawable != -1) {
                titleBarRightBtn.setBackgroundResource(rightButtonDrawable);
            }
        }
        typedArray.recycle();
    }

}

public void setTitleClickListener(OnClickListener onClickListener) {
    if (onClickListener != null) {
        titleBarLeftBtn.setOnClickListener(onClickListener);
        titleBarRightBtn.setOnClickListener(onClickListener);
    }
}

public Button getTitleBarLeftBtn() {
    return titleBarLeftBtn;
}

public Button getTitleBarRightBtn() {
    return titleBarRightBtn;
}

public TextView getTitleBarTitle() {
    return titleBarTitle;
}
}

4.正确地使用它

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">

<com.mumubin.demoproject.view.CustomTitleBar
    android:id="@+id/ctb_view"
    android:layout_width="match_parent"
    android:layout_height="45dp"
    app:right_button_drawable="@mipmap/sure"
    app:title_text="@string/app_name" />

<com.mumubin.demoproject.view.CustomTitleBar
    android:layout_width="match_parent"
    android:layout_height="45dp"
    android:layout_marginTop="4dp"
    app:title_background_color="@color/colorPrimary"
    app:title_text="@string/app_name"
    app:title_text_color="@color/colorAccent"
    app:left_button_text="左边"
    app:right_button_text="右边"/>

<com.mumubin.demoproject.view.CustomTitleBar
    android:layout_width="match_parent"
    android:layout_height="45dp"
    android:layout_marginTop="4dp"
    app:title_text_drawable="@mipmap/ic_launcher"
    app:title_background_color="@color/colorAccent"
    app:left_button_text="左边"
    app:right_button_text="右边"/>
</LinearLayout>

titlebar.png